[Al/lpr]

Al/lpr
Hi all, first post. I am pretty knowledgeable, all things GM. I came a crossed a so called 1974 SD 455 rebuilt which should have been a Y8 490132 also there is a W8
Same year and HP both have casting # 490132, but the Y8 is the only one listed as a SD. Now this is where the plot changes. this guy bought this T/A brand new with a SD engine in 1974. drove it into the Ground, started to restore many years later rebuilt the Engine, body was pretty bad put QT,s on it reinstalled engine trailered it to his house, while taking it of the trailer the sub frame separated from the body. So he pulled the engine and scraped the car, now it is for sale. He sent me the casting # Y9 525740 clear as day. I looked it up and no such engine was ever produced with those numbers. Can any one here shed some light on this. I have not been stumped for many years